core.strings¶

Null-terminated string manipulation library for the kernel.

Overview¶

core.strings provides a comprehensive set of routines for working with null-terminated (pchar) strings in a bare-metal environment. Because the kernel cannot use the Free Pascal runtime library string support, all allocation is performed through the kernel heap (kalloc/kfree) and all operations work on raw pointer-based C-style strings. The unit covers string creation, copying, comparison, searching, case conversion, concatenation, substring extraction, replacement, and conversion to and from integer types. A built-in UnitTest procedure exercises the full API and reports results via syslog.

Dependencies¶

core.util — memcpy, memset, HexCharToDecimal
arch.x86.util — architecture-level utilities
memory.heap — kalloc, kfree
core.ds.lists — transitively required
io.syslog — test output (implementation section only)

Functions and Procedures¶

stringNew¶

function stringNew(size : uint32) : pchar;

Allocates a new zero-initialised string buffer of size bytes plus a null terminator. Returns a pointer to the buffer.

stringCopy¶

function stringCopy(str : pchar) : pchar;

Allocates and returns a heap copy of str.

stringSize¶

function stringSize(str : pchar) : uint32;

Returns the length of str in characters, excluding the null terminator. Returns 0 for nil.

stringEquals¶

function stringEquals(str1, str2 : pchar) : boolean;

Returns true if str1 and str2 have identical length and content.

stringToUpper¶

function stringToUpper(str : pchar) : pchar;

Returns a heap-allocated copy of str with all lowercase ASCII letters converted to uppercase.

stringToLower¶

function stringToLower(str : pchar) : pchar;

Returns a heap-allocated copy of str with all uppercase ASCII letters converted to lowercase.

stringConcat¶

function stringConcat(str1, str2 : pchar) : pchar;

Returns a heap-allocated string containing str1 followed by str2.

stringTrim¶

function stringTrim(str : pchar; length : uint32) : pchar;

Returns a heap-allocated copy of str truncated to at most length characters. If length exceeds the string length, the full string is copied.

stringSub¶

function stringSub(str : pchar; start, size : uint32) : pchar;

Returns a heap-allocated substring of str beginning at byte offset start with at most size characters. Returns an empty string if start is past the end. If start + size exceeds the string length, the result is clamped to the end.

stringMatchAt¶

function stringMatchAt(str : pchar; pos : uint32; find : pchar) : boolean;

Returns true if find matches the characters in str starting at position pos. An empty find always returns true.

stringIndexOf¶

function stringIndexOf(str, find : pchar) : sint32;

Returns the zero-based index of the first occurrence of find within str, or -1 if not found. An empty find returns 0.

stringContains¶

function stringContains(str : pchar; sub : pchar) : boolean;

Returns true if sub appears anywhere within str.

stringReplace¶

function stringReplace(str, find, replace : pchar) : pchar;

Returns a heap-allocated copy of str with the first occurrence of find replaced by replace. If find is not present, a copy of str is returned unchanged.

stringToInt¶

function stringToInt(str : pchar) : uint32;

Parses a decimal integer string and returns its uint32 value. Non-digit characters are ignored.

intToString¶

function intToString(i : uint32) : pchar;

Returns a heap-allocated decimal string representation of i.

hexStringToInt¶

function hexStringToInt(str : pchar) : uint32;

Parses a hexadecimal string (no 0x prefix) and returns its uint32 value.

boolToString¶

function boolToString(b : boolean; ext : boolean) : pchar;

Returns a heap-allocated string for the boolean b. When ext is true, returns 'true' or 'false'; when false, returns '1' or '0'.

UnitTest¶

procedure UnitTest;

Runs the complete string function test suite and logs a pass/fail summary to syslog under the 'STRINGS' channel.

Notes¶

All functions returning pchar return newly heap-allocated strings. Callers are responsible for freeing the result with kfree when it is no longer needed.

stringReplace replaces only the first occurrence of find. There is no bulk-replace variant.